The weathered mantle
developed on welded ignimbritic formations of Dschang (Western Cameroon)
constitute for population living in the vicinity, the raw material use to
manufacture building blocks. However, many defects have been noticed on houses
built using these blocks such as cracking, swelling and low compressive
resistance of blocks.
The purpose of this
study is to investigate the physical and geotechnical properties of these soil
materials and their suitability in manufacturing Stabilized Earth Blocks (SEB)
for optimized local constructions by testing their physico-mechanical
characteristics. Results of these investigations, reveal two major types of
soil profiles: the soil profile from top hill (Meka’a Profile) and the soil
profile of downhill (Mingou Profile). These soil profiles are well-developed
with three main horizons (A, B and C). The surrounding population has been
using materials from B horizons (middle unit of soil profiles) for the
manufacture of SEB. These materials are mainly composed of quartz (12 – 31%),
goethite (17 – 22%), kaolinite (8 –18%) and gibbsite (23 – 44%). They display
high value of moisture content (48 – 61%) and are very porous (47%). Grain size
analysis classified these materials as fine-grained particles (47 – 65%) and so
do other geotechnical classifications systems such as HRB, GTR and LCPC. The
Atterberg limits reveal that they have high plasticity in nature with
plasticity index ranges from 39 to 53.8%.
Satisfactory results
were obtained when the weathered materials was stabilized with cement (CPJ 35)
above 6%. Flexural strength tests ranged from 2.11 – 2.44 MPa and compressive
strength ranged from 2.68 – 3.53 MPa. Nevertheless, some corrections are
necessary to enhance these characteristics. This can be carried out by grain
size distribution correction or the use of any type of chemical stabilizer.
However, some more
detailed specific tests are still required in a bid to optimize the suitability
of weathered ignimbrites for stabilized earth blocks production.